WASHINGTON — Republican senators staged a surprise boycott of a committee meeting and stalled the confirmation of President Obama’s nominee to lead the Environmental Protection Agency, a move that underscores how bitter battles over some Cabinet nominations have strained the president’s relationship with Congress.

Gina McCarthy, a Massachusetts native who was a top environmental official under former Republican governor Mitt Romney and several other governors, has the backing of environmental and some business groups, making her a rather unlikely candidate for such an openly partisan maneuver.

But the EPA’s mission of protecting the environment, which often means greater restrictions on businesses that pollute, makes it a frequent target of Republicans who say the agency abuses its broad powers and hampers economic growth. When all eight Republicans on the Senate Committee on Environment and Public Works on Thursday said they would not show up for a key vote on McCarthy’s nomination, it denied a quorum for the vote and blocked her name from reaching the full Senate for consideration.

“For too long, EPA has failed to deliver on the promises of transparency espoused by President Barack Obama, former administrator Lisa Jackson, and by Gina McCarthy,” said Republicans on the committee, led by Senator David Vitter of Louisiana, in a statement.

Democrats insisted that it was a temporary setback and that McCarthy would get a vote on the Senate floor.

Committee chairwoman Barbara Boxer of California said in an interview that Democrats were blindsided, with little notice, and called it a “cowardly stance.” She vowed to press on, most likely next week, even if she has to hold a meeting without any Republican senators present to hold a committee vote.

“The reason they don’t want to show up is they have absolutely no case to make,” Boxer said.

Republicans on the environmental panel pointed out in a letter to Boxer on Thursday that Democrats had waged an identical boycott in 2003, stalling committee approval for President Bush’s EPA nominee, Michael Leavitt, for two weeks.

They argued that Boxer could not hold a meeting without at least two Republicans present, something Boxer and several fellow Democrats disputed.

“Did the GOP really just boycott the confirmation vote for the EPA nominee? The obstruction is reaching new levels of absurdity,’’ said Dan Pfeiffer, a senior White House adviser, on Twitter.

In addition to outrage, Thursday’s action prompted concern from Vermont Senator Bernie Sanders, an independent who aligns with Democrats, that McCarthy could be the subject of a Republican filibuster once her nomination reaches the full Senate, something Democrats said would portend a new level of dysfunction.

Sanders said Democrats could have trouble mustering 60 votes to overcome a filibuster and urged colleagues on the environmental committee to push her nomination through as soon as possible to avoid a prolonged battle.

Even if McCarthy is ultimately confirmed, Thursday’s action forces the EPA to operate longer without a permanent leader, a now-familiar predicament for the agencies that run Washington in an era of near-constant discord on Capitol Hill.

The EPA has lacked a permanent chief since Jackson stepped down in mid-February. Environmental leaders compared the lack of an EPA administrator to a police department without a chief.

“It’s taking unnecessary chances with community health and safety,” said Cindy Luppi, New England director of Clean Water Action, a group that works to elect environment friendly candidates. “The EPA has on deck right now a number of key decision points that protect our air and protect our drinking water. These are serious issues with which politicians should not play partisan games.”

Seth Kaplan, vice president for policy and climate advocacy at the Boston-based Conservation Law Foundation, said that without a permanent administrator, the EPA will be less likely to issue major rules and launch initiatives, such as regulations of greenhouse gas emissions from power plants. It will be especially difficult for the EPA to set budget priorities without a chief, he said.

“We’re in a moment when guidance from the top is especially important to make those priority decisions,” said Kaplan. He added he routinely gets “out of office” e-mail responses from EPA officials saying they are on furloughs because of mandatory federal government spending cuts known as sequestration — another symbol of the capital’s dysfunction.

McCarthy, now the EPA’s assistant administrator for air and radiation, worked under five Massachusetts governors, including in Romney’s administration, where she held a top policy post. The Canton native then led the Connecticut Department of Environmental Protection before moving to the EPA in 2009. Obama appointed her to lead the EPA in early March.

Republicans said the agency had balked on four of five requests for information, including what McConnell said were the “underlying data used to justify EPA’s job-killing regulations.”

“It should come as no surprise that the Obama administration continues to stonewall reasonable information requests from Republicans on the EPW committee, information that is crucial to their advice-and-consent role in this nomination,” McConnell said in a statement.

Democrats said McCarthy had answered more than 1,000 questions, which they called a record, and accused Republicans of stalling because they did not like the answers.

“This type of blanket, partisan obstruction used to be unheard of,” Senate majority leader Harry Reid, a Nevada Democrat, said from the Senate floor.

On Wednesday, Republicans delayed, for the second time in two weeks, a vote on Tom Perez’s nomination as head of the Department of Labor.

“Instead of a fair and constructive confirmation process, Republicans have chosen to play partisan, political games with dozens of President Obama’s appointees,” Reid said. “I assure you Ms. McCarthy will have her day in the Senate.”

Massachusetts senators said the latest action surprised them.

“Gina is a proud Massachusetts native who has dedicated her life to public service,” said Senator William “Mo” Cowan, a Democrat. “Working for Republican and Democratic administrations alike, Gina has committed her career to protecting our public health, conserving our natural resources, and leading state and federal agencies that balance these important goals with our economic interests.”

Despite the new questions around McCarthy’s nomination, several other Democrats said they agreed with Reid that McCarthy’s nomination would reach the floor and win approval on a simple majority vote.

“I don’t think [the nomination is] in any trouble. I just think this is an outrageous boycott,” said Tom Udall, a New Mexico Democrat who serves on the environmental committee.

Senator Ben Cardin, a Maryland Democrat on the panel, said forcing a supermajority of 60 votes to approve McCarthy would set a new standard for gridlock in the Senate.

“They can use procedure for a while, but at the end of the day, this will become somewhat of a nuclear option to use a 60-vote threshold for a noncontroversial Cabinet position,” Cardin said.